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Open Access Research article

Validation of the GenoType® MTBDRplus assay for diagnosis of multidrug resistant tuberculosis in South Vietnam

Mai NT Huyen1, Edine W Tiemersma23*, Nguyen TN Lan1, Frank GJ Cobelens3, Nguyen H Dung1, Dinh N Sy4, Tran N Buu1, Kristin Kremer5, Pham T Hang1, Maxine Caws6, Richard O'Brien7 and Dick van Soolingen58

Author Affiliations

1 Phạm Ngọc Thạch hospital, 120 Hung Vuong, district 5, Ho Chi Minh City, Viet Nam

2 KNCV Tuberculosis Foundation, PO Box 146, 2501 CC The Hague, The Netherlands

3 Center for Poverty-related Communicable Diseases, Amsterdam Institute of Global Health and development, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands

4 National Lung Hospital, 463 Hoang Hoa Tham, Ba Dinh district, Ha Noi, Viet Nam

5 Tuberculosis Reference Laboratory, RIVM, PO Box 1, 3720 BA Bilthoven, The Netherlands

6 Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Hospital for Tropical Diseases,190 Ben Ham Tu, District 5, Ho Chi Minh City, Viet Nam

7 Foundation for Innovative New Diagnostics (FIND), Avenue de Budé 16, 1202 Geneva, Switserland

8 Departments of Pulmonary Diseases and Medical Microbiology, Radboud University, PO box 9101, 6500 HB Nijmegen, The Netherlands

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BMC Infectious Diseases 2010, 10:149  doi:10.1186/1471-2334-10-149

Published: 3 June 2010

Abstract

Background

To control multidrug resistant tuberculosis (MDR-TB), the drug susceptibility profile is needed to guide therapy. Classical drug susceptibility testing (DST) may take up to 2 to 4 months. The GenoType® MTBDRplus test is a commercially available line-probe assay that rapidly detects Mycobacterium tuberculosis (MTB) complex, as well as the most common mutations associated with rifampin and isoniazid resistance.

We assessed sensitivity and specificity of the assay by using a geographically representative set of MTB isolates from the South of Vietnam.

Methods

We re-cultured 111 MTB isolates that were MDR, rifampin-resistant or pan-susceptible according to conventional DST and tested these with the GenoType® MTBDRplus test.

Results

By conventional DST, 55 strains were classified as MDR-TB, four strains were rifampicin mono-resistant and 52 strains were susceptible to all first-line drugs. The sensitivity of the GenoType® MTBDRplus was 93.1% for rifampicin, 92.6% for isoniazid and 88.9% for the combination of both; its specificity was 100%. The positive predictive value of the GenoType® MTBDRplus test for MDR-TB was 100% and the negative predictive value 90.3%.

Conclusions

We found a high specificity and positive predictive value of the GenoType® MTBDRplus test for MDR-TB which merits its use in the MDR-TB treatment program in Vietnam.